Ten physiognomic types of women, Coquettish type Utamaro was a Japanese artist - who studied the woman sensuality. One of his discovers was the slightly opened mouth. Next time you ask your model to slightly open her mouth you'll know who invented this :)
Kitagawa Utamaro's bust-style portraits of beauties made him popular in his day and continue to keep his name alive today. This print is called “The Fickle Type” from the series Ten Types in the Physiologic Study of Women.